Polymerization processes for using dilute multicomponent feeds (LAW624)

ABSTRACT

The invention relates to a method of forming carbon monoxide-containing polymers from multi-component syngas feeds and at least one vinyl comonomer. Feeds useful in the practice of the invention comprise ethylene in an amount ranging from about 5 to about 40 mole %, carbon monoxide is an amount ranging from about 1 to about 40 mole %, hydrogen in an amount ranging from about 4 to about 55 mole %, carbon dioxide in an amount ranging from about 3 to about 10 mole %, and methane in an amount ranging from about 4 to about 85 mole %. The feed may also include acetylene in an amount ranging up to about 10 mole %. The feed may contain at least one free radical-polymerizable vinyl comonomer, or a cofeed containing such a comonomer can be used.

FIELD OF THE INVENTION

The invention is directed towards a polymerization process for makingcopolymers from feeds of ethylene, carbon monoxide, and at least onevinyl co-monomer, the feeds preferably being derived from hydrocarbonconversion processes.

BACKGROUND OF THE INVENTION

Ethylene copolymers with CO, and another vinyl comonomer are prepared athigh pressure, high temperature from high purity monomer streams,especially streams having a low hydrogen concentration.

Multicomponent syngas-type feeds, containing ethylene, carbon monoxide,hydrogen, carbon dioxide, and methane are formed from various gasconversion processes, and are becoming increasingly abundant. Using suchfeeds for polymerization would be beneficial. However, such feeds arenot considered to have sufficient purity for polymerization because theycontain substantial amounts of reactive species such as hydrogen andacetylene.

There is therefore a need for a process for forming carbon monoxidecontaining copolymers from multicomponent feeds.

SUMMARY OF THE INVENTION

The invention is a method for polymerizing ethylene-carbon monoxide withat least one vinyl monomer (X). Such polymers may be designated E/CO/X.The method comprises forming copolymers under copolymerizationconditions from a feed of ethylene, carbon monoxide, hydrogen, carbondioxide, methane, and at least one vinyl comonomer selected from thegroup consisting of free radical polymerizable vinyl monomers.

More specifically, the feed contains ethylene in an amount ranging fromabout 5 to about 40 mole %, carbon monoxide in an amount ranging fromabout 1 to about 40 mole %, hydrogen in an amount ranging from about 4to about 55 mole %, carbon dioxide in an amount ranging from about 3 toabout 10 mole %, and methane in an amount ranging from about 4 to about85 mole %. The feed may also include acetylene in an amount ranging upto about 10 mole %.

Polymerization conditions range in temperature from about 50 to about230° C., range in pressure from about 100 to about 30,000 psi, andinclude a radical initiator having an appropriate half-life.

DETAILED DESCRIPTION OF THE INVENTION

The invention is based on the discovery that ethylene-carbon monoxidepolymerization processes using multicomponent syngas feeds facilitatecopolymerization with other vinyl monomers. For example, ethylene andoctene are difficult to copolymerize under free radical polymerizationconditions. The reactivity ratio for ethylene is 3.1 and the reactiviyratio for others is 8. Consequently, both ethylene and octene wouldrather homopolymerize than copolymerize. However, when MCS is used as asource of ethylene, incorporation of at least one vinyl comonomer isenabled.

Without wishing to be bound by any theory, it is believed the ECOradical is more reactive than an ethylene or octene radical would betoward ethylene or octene. Moreover, RCO radicals cannot add CO. Thusincorporation of octene is facilitated within excluded sequences of CO.Moreover, it is believed that the hydrogen present in such feedsbeneficially acts as a mild chain transfer agent.

Feeds useful in the practice of the invention comprise at least oneolefinically unsaturated compound in an amount ranging from about 5 toabout 40 mole %, carbon monoxide in an amount ranging from about 1 toabout 40 mole %, hydrogen in an amount ranging from about 4 to about 55mole %, carbon dioxide in an amount ranging from about 3 to about 10mole %, and methane in an amount ranging from about 4 to about 85 mole%. The feed may also include at least one acetylenically unsaturatedcompound in an amount ranging up to about 10 mole %. The feed maycontain at least one free radical-polymerizable vinyl comonomer, or acofeed containing such a comonomer can be used. Vinyl monomers useful inthe invention include ethylene, α-olefins (C₃ to C₃₀) such as propylene,butene, 1-octene, 1-octadecene, styrene and styrene derivatives such asα-methylstyrene, p-methylstyrene, tetrafluoroethylene, vinyl chloride,vinyl acetate, isobutyl vinyl ether, methyl vinyl ketone,1-vinylpyrrolidone, acrylic acid, methacrylic acid, methylacrylate,methylmethacrylate, acrylonitrile, acrylamide, acrolein, allyl alcohol,allyl chloride, allyl acetate, mixtures thereof, and similar materials.While vinyl comonomer concentration in the feed may range from zero ortrace amounts to about 95 mole %, the preferred concentration rangesfrom about 5 mole % to 80 mole %.

The olefinically unsaturated compounds (i.e., olefins) useful in theinvention typically contain up to 20 carbon atoms, preferably up to 10carbon atoms. They may contain heteroatoms; however, it is preferredthat the olefinically unsaturated compounds are hydrocarbons. Apreferred class of olefinically unsaturated hydrocarbons are aliphaticmono-olefins, in particular α-olefins of which ethylene is particularlypreferred.

The acetylenically unsaturated compounds useful in this inventionpreferably contain up to 20 carbon atoms, more preferably up to 10carbon atoms. Preferably they are hydrocarbyl compounds, and they mayvary widely in structure. They may also contain heteroatoms. Preferably,the acetylenically unsaturated compounds have at most one organic groupattached to the ethynyl groups. More preferably the acetylenicallyunsaturated compound is of the general formula R—C≡CH where R denotes ahydrogen atom or a hydrocarbyl group. Hydrocarbyl groups R may be arylgroups, such as phenyl, 4-methoxyphenyl, 3-chlorophenyl and naphthylgroups, or (cyclo)alkyl groups, such as methyl, ethyl, 2-propyl,2-butyl, cyclohexyl and 2-methylhexyl-1 groups. For example, when the Rgroup is a methyl groupthen the acetylenically unsaturated compound ispropyne, and when the R group is hydrogen then the acetylenicallyunsaturated compound is acetylene. A mixture of acetylenicallyunsaturated compounds may be involved, but a single acetylenicallyunsaturated compound is preferred.

Feeds used in the practice of the invention contain a combined CO andolefin concentration of no more than about 35 mole %. The preferred feedis derived from hydrocarbon, preferably from gas conversion processes,and still more preferably from natural gas conversion processes.Oxidative coupling and methane partial oxidation of a methane-containinggas followed by ethane quench are examples of such a reaction. A mixtureof feeds resulting from such processes is also within the scope of theinvention. In addition to carbon dioxide, inert diluents such as methanecan be present in the feed in amounts ranging from about 4 mole % toabout 85 mole %. Importantly, feeds used in the practice of theinvention may contain up to 55 mole % H₂. The preferred feed contains 5to 55 mole % hydrogen, and is formed in a methane-derived hydrocarbonsynthesis reaction. The methane-containing gas may be a natural gas or asynthetic gas.

CO-containing polymers of the present invention are formed in freeradical polymerization processes using,organic peroxides as a freeradical initiator according to conventional methods. Representativeinitiators include dialkyl peroxides such as ditertiary-butyl peroxide,2,5-dimethyl-2,5-ditertiary-butyl-peroxyhexane, di-cumyl peroxide; alkylperoxides such as tertiary-butyl hydroperoxide, tertiary-octylhydroperoxide, cumene hydroperoxide; aroyl proxides such as benzoylperoxide; peroxy esters such as tertiary-butyl peroxypivalate,tertiary-butyl-perbenzoate; and compounds such asazo-bis-isobutyronitrile. Free radical initiators with an appropriatehalf-life at a reaction temperature ranging from about 50° C. to about200° C. can be used, and of these, t-butyl peroxypivalate, which has ahalf life of about 10 hours at 66° C., is preferred.

Such feeds and initiators are useful for forming CO-containing polymersunder copolymerization conditions at temperatures ranging from about 50to about 230° C., preferably from about 50° C. to about 100° C.,pressures ranging from about 100 to about 30,000 psi, preferably fromabout 100 psi to about 3,000 psi, and in the presence of a free radicalinitiator having an appropriate half life.

Preferably, the reaction occurs in the presence of a solvent. Suitablesolvents include toluene, benzene, dioxane, pentane, heptane, hexane,propylene oxide, cyclohexane, and the like. Hexane is preferred.

The term “polymer” as used herein is a macromolecule formed from atleast one monomer or monomer source; the term “copolymer” is amacromolecule formed from at least two monomers or monomer sources.

The copolymers and polymers prepared in accord with this invention maybe recovered from the polymerization of mixture using conventionalmethods, for example, by filtration or by evaporation of the diluent.They may be brought into the desired shape by the usual formingtechniques, such as cold or hot pressing. Alternatively, thepolymerization is carried out in such a way that the copolymer is formedin the desired shape, such as by solution polymerization in a thin layerand subsequent removal of the diluent, which yields the copolymer in theform of a film.

The number average molecular weight (“Mn”) of the polymers formed inaccordance with the invention range from about 200 to about 1,000,000.Mn preferably ranges from 300 to 100,000 and more preferably from 500 to50,000.

The degree of branchiness of the copolymer chains and the number ofmonomer units originating in the monomers with polymerizablecarbon-carbon unsaturation relative to the number of carbon atomsoriginating in carbon monoxide will both, at least in part, determinethe regularity of the polymer chains and thereby also some of theproperties of the copolymer, for example the crystallinity andsolubility. The ratio of the number of monomer units originating in theolefinically unsaturated compound and, if present, the acetylinicallyunsaturated compound to the number of carbon atoms originating in carbonmonoxide is preferably at most about 99:1, more preferably in the rangeof from about 90:1 to about 1:1, and still more preferably from about95:1 to about 1:1. However, where the presence of additional cure sitesare desired or beneficial, the preferred range of acetyleneincorporation should be less than 10%.

The polymers prepared according to the practice of the invention arenon-linear polymers having a total number of branches per 1000 carbonatoms ranging from about 60 to about 300. Branchiness is measured by ¹³Csolution NMR in deutero chloroform using a Cr(AcAc)₃ relaxation agent.The number of C₁ branches per 1000 carbon atoms was measured at about20.1 ppm; the number Of C₂ branches, per 1000 carbon atoms was measuredat about 11.3 ppm; the number of C₃ was measured at about 14.7 ppm; andthe number of C₄ branches was measured at about 14.2 ppm.

The polymers prepared in accord with this invention areparaffin-soluble. The term “paraffin” as used herein is a normal, iso,or straight chain alkane.

The invention is further described in the following non-limitingexamples.

EXAMPLE 1

A 300 ml autoclave was charged with 150 ml pure n-hexane and 0.609 gramsof a 75% solution of t-butyl peroxypivalate in mineral spirits. Thereactor was sealed and purged with purified nitrogen. The reactor wasinitially spiked with ethylene by pressurizing to 170 psig andsubsequently pressurizing with multicomponent syngas (MCS) mixture(ethylene 5.4%, carbon monoxide 1.3%, carbon dioxide 7.4%, hydrogen 4.6%and methane 81.3%) to 500 psig. In all examples, relative componentconcentrations are in mole %, unless otherwise noted. The temperaturewas raised to 66° C. while stirring and the autoclave was pressurizedwith MCS feed to 700 psi, which was maintained for 24 hours. The reactorwas allowed to cool to room temperature and was then depressurized. Thehexane was removed on rotary evaporator to obtained 2.58 g the product.

The product was characterized by IR and GPC. The FTIR spectrum of theproduct showed a very strong peak at 1718 cm⁻¹ due to carbonyl group,indicating incorporation of carbon monoxide in the product. The GPC ofthe product (polystyrene standards, THF solvent) showed the Mn of 406and Mw of 845.

This example shows that an ethylene feed and a relatively dilute MCSfeed are useful polymerization co-feeds.

EXAMPLE 2

In this example, the polymerization reaction described in Example 1 wasrepeated with a higher level of ethylene spiking, 412 psig initialreactor pressurization compared to 170 psig reactor pressurization inexample 1, in order to gauge the effect of ethylene concentration onproduct molecular weight.

The product was characterized by IR and GPC. The FTIR spectrum of theproduct showed a very strong peak at 1718 cm⁻¹ due to carbonyl group,indicating incorporation of carbon monoxide in the product. The GPC ofthe product (polystyrene standards, THF solvent) showed the Mn of 1000and Mw of 2550.

The higher product molecular weight relative to the molecular weight ofthe product of example 1 shows that ethylene spiking level is aneffective method for molecular weight control.

EXAMPLE 3-7

Carbon monoxide containing polymers was synthesized using an MCS with avinyl acetate cofeed using free-radical polymerization. These examplesshow that ethylene-carbon monoxide copolymers can be formed with a vinylcomonomer and that molecular weight can be controlled. Polymerizationreaction conditions were as follows:

Any inhibitor present with the vinyl acetate was removed by passing thevinyl acetate through an inhibitor removal column.

A 300 ml autoclave reactor was charged with solvent (n-hexane) and at-butyl peroxypivalate initiator. Purified vinyl acetate was added withsolvent in the autoclave (examples 3 and 6) or added into bomb with theMCS feed (examples 4,5 and 7). The reactor was sealed and purged withpurified nitrogen. The reactor was pressurized to 275 psig with arelatively impure (or “dirty”) MCS mixture (ethylene 9.2%, carbonmonoxide 21.5%, carbon dioxide 3.0%, hydrogen 55.23%, acetylene 80.1%,and methane 3.06%). The temperature was raised to 66° C. while stirring,and the temperature was maintained for 24 hours, after which the reactorwas allowed to cool to room temperature and was depressurized. Thehexane was removed on rotary evaporator to obtain the product. Table-1sets forth polymerization details.

TABLE 1 Co- monomer Initiator Vinyl Solvent t-butyl Example MCS AcetateHexane Temp. peroxypivalate Yield Number Feed (ml) (ml) (° C.) (g) (g)Comments 3 2 10 140 66 0.615 8.5 Without bomb 4 2 10 125 66 0.614 10.7 VA added with MCS, with bomb 5 2  5 125 66 0.618 6.7 VA added with MCS,with bomb 6 2  5 150 66 0.622 5.0 Without bomb 7 2  2 125 66 0.618 2.7VA added with MCS, with bomb

MCS feed 2: Ethylene 9.2%, Carbon Monoxide 21.5%, Carbon Dioxide 3.0%,Hydrogen 55.23%, Acetylene 8.01%, and Methane 3.06%.

Table-2 sets forth characterization results for these polymers.

TABLE 2 Example NMR mole % GPC Number Composition (Mn) GPC (Mw) 3 E:26;VA:70; CO:4 1390 6180 4 E:22; VA:76; CO:3 1770 7380 5 E:32; VA:63; CO:51320 4360 6 E:39; VA:55; CO:5 1070 3270 7 E:56; VA:35; CO:9 730 1620

In example 4, NMR measurements revealed a double bond consistent withacetylene monomer incorporation and nonlinear (branched) polyethylenesegments.

EXAMPLE 8-10

Carbon monoxide-containing polymers using a relatively dilute MCS cofeedwith styrene of 1-octene were synthesized using free-radicalpolymerization as follows:

An inihibitor removal column removed any inhibitor in the styrene.

The polymerization conditions were similar to those set forth inExample 1. A 300 ml autoclave was charged with solvent (n-hexane) andt-butyl peroxypivalate initiator. Purified monomer (styrene in examples9 and 10 and octene in example 8) was added with solvent (example 8) inthe autoclave or was added into bomb along with the MCS feed (examples 9and 10). The reactor was sealed and purged with purified nitrogen. Thereactor was pressurized to 700 psig with the MCS mixture. Thetemperature was raised to 66° C. while stirring, and was maintained for24 hours. The reactor was allowed to cool to room temperature, and wasthen depressurized. The hexane was removed on a rotary evaporator toobtain the product. Table-3 sets forth the polymerization details.

TABLE 3 Initiator Solvent t-butyl Example MCS Co- Hexane Temp.peroxypivalate Yield Number Feed monomer (ml) (° C.) (g) (g) Comments 81 Octene 150 66 0.630 2.9 Without bomb 20 g 9 1 Styrene 125 66 0.612 1.5Styrene added  5 g with MCS, with bomb 10  1 Styrene 125 66 0.606 1.9Styrene added  1 g with MCS, with bomb

MCS feed 1: Ethylene 5.4%, Carbon Monoxide 1.3%, Carbon Dioxide 7.4%,Hydrogen 4.6%, and Methane 81.3%.

Table-4 sets forth characterization results for these polymers.

TABLE 4 Example NMR mole % GPC Number Composition (Mn) GPC (Mw) 8 8601010 9 E:30; sty:70; CO:trace 2380 3450 10 E:59; sty:41; CO:trace 590780

No double bonds indicating acetylene incorporation were observed in theNMR results, consistent with the MCS feed employed.

EXAMPLE 11

Carbon monoxide containing polymers using an MCS feed with a styrenecofeed was synthesized using free-radical polymerization as follows:

An inihibitor removal column removed any inhibitor in the styrene. Thepolymerization conditions were similar to those set forth in Example 3.A 300 ml autoclave reactor was charged with solvent n-hexane and t-butylperoxypivalate initiator. One gram of purified styrene was introducedinto the bomb so that it could be added with MCS feed. The reactor wassealed and purged with purified nitrogen. The reactor was pressurized to200 psig with the MCS mixture (Ethylene 9.2%, Carbon Monoxide 21.5%,Carbon Dioxide 3.0%, Hydrogen 55.23%, Acetylene 8.01%, and Methane3.06%). The temperature was raised to 66° C. while stirring, and wasmaintained for 24 hours. The reactor was allowed to cool to roomtemperature, and was then depressurized. The hexane was removed onrotary evaporator to obtain the product.

The IR spectrum of the product showed a characteristic carbonyl peak at1715 cm-1 along with polystyrene peaks. The carbonyl peak in the IRshows that carbon monoxide has been incorporated into the product.

What is claimed is:
 1. A method for producing a non-linear polymer fromethylene, carbon monoxide and at least one vinyl comonomer, comprisingthe step of reacting a feed under copolymerization conditions with atleast one free radical polymerizable vinyl monomer, the feed comprisingan olefinically unsaturated compound in an amount ranging from about 5to about 40 mole %, carbon monoxide in an amount ranging from about 1 toabout 40 mole %, hydrogen in an amount ranging from about 4 to about 55mole %, carbon dioxide in an amount ranging from about 3 to about 10mole %, methane in an amount ranging from about 4 to about 85 mole % andan acetylenically unsaturated compound in an amount ranging up to about10 mole %, whereby a non-linear polymer is produced, and further whereinthe copolymerization conditions range in temperature from about 50 toabout 230° C., range in pressure from about 100 to about 30,000 psi andinclude a free radical initiator having an appropriate half-life.
 2. Themethod of claim 1 wherein the copolymerization is conducted in thepresence of a solvent selected from the group consisting of toluene,benzene, dioxane, pentane, heptane, hexane, propylene oxide,cyclohexane, and mixtures thereof.
 3. The method of claim 1 wherein thefree radical initiator is selected from the group consisting ofditertiary-butyl peroxide,2,5-dimethyl-2,5-ditertiary-butyl-peroxyhexane, di-cumyl peroxide,tertiary-butyl hydroperoxide, tertiary-octyl hydroperoxide, cumenehydroperoxide, benzoyl peroxide, tertiary-butyl peroxypivalate,tertiary-butyl-perbenzoate, azo-bis-isobutyronitrile and mixturesthereof.
 4. The method of claim 1 wherein the feed is derived from ahydrocarbon conversion process.